A display device for a medical apparatus including a projection surface arranged on the medical apparatus and configured to present a predetermined display content in a way visible to a user of the medical apparatus, and a projection device arranged on the medical apparatus and configured to project the predetermined display content from a rear side of the projection surface onto the projection surface. The projection surface and the projection device are configured as a head-up display unit for visual field presentation of the display content, and the medical apparatus may be an apparatus for carrying out extracorporeal blood treatment including the display device.